JPH04198965A - Image forming device - Google Patents

Abstract

PURPOSE:To easily adjust lateral alignment, to reduce manufacturing cost and to attain high speed performance by altering the timing when an image forming means starts the scanning of image information based on the information outputted from a position detecting means which detects the position in a main scanning direction of a recording material carried by the use of a carrying means. CONSTITUTION:A reference value in the main scanning direction is predetermined at every paper feeding table 71 and the timing of image formation is adjusted based on the position detecting the recording material 41. Also, the variables of the main scanning direction after the image formation is measured. Based on the measured value, the timing of image formation at every paper feeding table 71 can be altered and inputted. Thus, the lateral registration characteristic difference at every paper feeding table 71 can be easily adjusted at every paper feeding table 71. Also, the constitution can be simplified and the manufacturing costs can be reduced. Further, the high speed performance is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus, and particularly to a lateral registration adjustment technique in an electrophotographic digital copying machine, an inkjet recording apparatus, or the like.

[Conventional technology]

Conventionally, electrophotographic digital copying machines have been the main type of image forming apparatus that digitally forms images.

There are inkjet recording devices and thermal transfer recording devices. An electrophotographic digital copying machine moves a drum or belt-shaped photoreceptor and directs an output beam from a solid-state scanner such as a laser scanner or a liquid crystal shutter in a direction approximately perpendicular to the direction of movement of the photoreceptor (hereinafter referred to as the main scanning direction). A recording material support that forms an electrostatic latent image on a photoconductor by scanning the photoconductor, develops this electrostatic latent image with toner in a developing section, and moves the visualized toner image in the same direction as the photoconductor. A recorded image is obtained by transferring the image onto a transfer paper that is suctioned and held on a barrel transfer belt and fixing it in a fixing section. In addition, an inkjet recording device attracts and holds paper or specially processed recording material on a conveyor belt that serves as a recording material support, and while moving this conveyor belt, the scanner of the inkjet head scans in the main scanning direction or aligns it in rows. The images are visualized all at once. A thermal transfer recording device uses a thermal transfer head as its scanner.

In the conventional apparatus described above, the positional deviation of the image after recording is measured, and based on this measurement, the mounting position of the paper feeder is moved and adjusted relative to the main body of the apparatus, and the paper feeder is fixed with screws. In so-called front-loading paper feeding devices that are multistage and are attached to and removed from the front of the device, the position of the recording material when it is held by the registration rollers that take image timing is detected. Based on this, there is a device that slides and adjusts the registration roller in the main scanning direction using a solenoid or the like.

[Problems to be Solved by the Invention] However, in the above conventional example, the belt or registration roller of the paper feeding device is moved by detecting the position of the image after printing or the position of the recording material before printing for each recording paper. Therefore, there were problems to be solved such as high manufacturing costs and working costs, complicated internal mechanisms, etc., and difficulty in responding to higher speeds. Further, a recording medium of a specific size is not always provided in a predetermined paper feeding section, and when it is replaced, it is often impossible to determine what paper feeding configuration (cassette) will be used.

An object of the present invention is to solve the above-mentioned problems, and to easily solve the problems described above, not only for a single paper feed unit but also for each of multiple paper feed units (for example, by calculating the difference between each paper feed tray for each paper feed tray). It is an object of the present invention to provide an image forming apparatus which can be adjusted to a high speed, which reduces manufacturing costs, has a simplified internal mechanism, and which can improve performance with respect to speeding up.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a recording material supplying means for supplying a recording material along with an image forming operation, and a recording material supplying means for supplying a recording material in accordance with an image forming operation. An image forming apparatus comprising: a conveying means for conveying to a forming position; and an image forming means disposed at the image forming position and forming an image by scanning in a main scanning direction perpendicular to the conveying direction of the recording material. , a position detection means for detecting the position in the main scanning direction of the recording material conveyed by the conveyance means, and a timing at which scanning of the image information of the image forming means is changed based on output information of the position detection means. The present invention is characterized in that it includes a timing control means for controlling the timing.

Further, as a preferred aspect of the present invention, the present invention includes a measuring means for measuring the amount of change in the image recording position in the main scanning direction on the recording material on which the image is formed by the image forming means, and the timing controlling means includes: The present invention is characterized in that the image information scanning start timing, which is a setting standard for each sheet feeding section of the recording material supplying means, is changed and adjusted based on the measurement results of the measuring means.

Further, as another preferred aspect of the present invention, the recording head of the image forming means has means for generating thermal energy that causes film boiling in the ink as energy used to eject the ink. Features.

[For production]

In the present invention, a setting reference value in the main scanning direction is predetermined for each paper feed tray, the image forming timing is adjusted based on the detected position of the recording material, and the amount of change in the main scanning direction after image formation is measured. Since it is possible to change the image forming timing for each paper feed table based on this measured value, it is possible to easily adjust the difference in lateral registration characteristics for each paper feed table. As described above, in the present invention, the position of lateral registration can be corrected by adjusting the image forming timing, so that the structure can be simplified, manufacturing costs can be reduced, and an improvement in high-speed performance can be expected.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the basic configuration of an embodiment of the present invention. In FIG. 1, A is a position detection means for detecting the position in the main scanning direction of the recording material conveyed by the conveyance means. B is a timing control means for changing the timing at which the image forming means C starts scanning image information based on the output information of the position detecting means A.

Further, D is a measuring means for measuring the amount of change in the image recording position in the main scanning direction on the recording material on which the image is formed by the image forming means C. The timing control means B changes and adjusts the image information scanning start timing, which is a setting standard for each paper feed tray of the recording material supply means, based on the measurement results of the measurement means.

Figure 2 shows the internal structure of an embodiment (referred to as the first embodiment) of an image forming apparatus to which the present invention is applied.

The apparatus of this example is an electrophotographic color image forming apparatus. In FIG. 2, four image forming means Pa, Pb,
Pc and Pd are arranged in a line. Each of the image forming means Pa to Pd has a dedicated electrophotographic photoreceptor drum 18a, 18b, 18c, and 18d, and around these drums are dedicated image forming process means, such as chargers 8a, 8b, 8c, 8d, developing sections 9a, 9b, 9c.

9d, transfer parts 19a, 19b, 19c, 19d,
Cleaning section 10a.

10b, 10c, 10d, and laser scanner exposure means 1a, lb, lc, which is a scanner that digitally forms image information as a latent image on a photoreceptor drum.
, ld, etc. are installed. Also, the photosensitive drum 18a
-d includes a cassette case 42 holding transfer paper 41 as a recording material, and a paper feeding device 40 for feeding the transfer paper 41 one by one to each of the image forming means Pa to Pd, and A transfer material conveying device 30 consisting of an endless transfer belt 4, which is a recording material conveying support body, which moves in the direction of the arrow in a manner penetrating each of the image forming means PaxPd described above, and the like are arranged.

Furthermore, a pair of rollers 1 for conveying the recording material in a timely manner is provided between the paper feeding device 40 and the transfer material conveying device 30.
6. An attraction charger 31 that electrostatically attracts the transfer paper 41 onto the transfer belt 4, a bias roller 5, and a position detection means 2 that detects the paper edge position of the transfer paper 41 are arranged.

In the above configuration, first, the transfer paper 41 is fed from the paper feeder 40 and stops once its leading edge is slightly pinched by the pair of rollers 16, and then the transfer paper 41 is fed by the image forming means Pa.
The transfer material is sent to the transfer material conveying device 30 in synchronization with the image forming process. Then, when the transfer paper 41 passes between the attraction charger 31 and the bias roller 5, it is electrostatically attracted onto the transfer belt 4, and then the position detection means 2
pass through. At this time, the position detection means 2 detects the position of the transfer paper 41 in the main scanning direction (direction in front of the apparatus).

Further, in the first image forming means Pa, the position detecting means 2
With the exposure start timing in the main scanning direction adjusted by the timing control circuit shown in FIG. 6 based on the detection information of The photoreceptor drum 18a is scanned to form an electrostatic latent image on the photoreceptor drum 18a. Next, the developing section 9a forms a visible image of yellow toner on the latent image.

On the other hand, the transfer paper 41 is conveyed while being electrostatically attracted and held on the transfer belt 4, and the yellow toner image previously formed on the photoreceptor drum 18a is transferred at a transfer section, that is, a transfer position 19a. Below, Part 2. 3rd゜Fourth image forming means P
Also in b, Pc, and Pd, the first image forming means Pa
Similarly, magenta, cyan, and black toner images are sequentially formed, and these toner images are transferred to the transfer paper 41.
Multiple transfers are performed sequentially on the top.

When such a transfer process is completed, the transfer paper 41 is separated from the transfer conveyance device 30 and the toner image is fixed by the fixing device 14, thereby obtaining a color image.

In addition, each photosensitive drum 1111a on which transfer has been completed
to 18d, residual toner is removed by cleaning sections 10a to 10d in preparation for the next latent image formation to be performed subsequently.

Next, with reference to FIGS. 3 and 4 showing enlarged main parts of FIG. 2, FIG. 5 showing the signal output timing, and FIG. 6 showing the timing control circuit, The relationship between the position detection operation of the transfer paper and the scanning start timing of the scanner will be described in detail.

First, in FIG. 3 showing the vicinity of the position detecting means 2 in detail, the transfer paper 41 conveyed by the paper feeding device 40 as described above is further transferred onto the transfer belt 4 of the transfer material conveying device 30 by the roller pair 16. The toner is fed and gradually attracted onto the transfer belt 4 from its leading edge by the adsorption charger 31 and the bias roller 5.

Thereafter, the end surface of the transfer paper 4I passes through an optical position detection means 2 such as a transmission type photocoupler in which a light emitting part and a light receiving part are integrated. This position detection means 2 is of a type in which the signal level of the sensor output of the light receiving section changes depending on the area covered by the transfer paper 41 over the light receiving section, and based on this signal level, the position of the transfer paper 41 in the direction of arrow C (main position in the scanning direction).

Further, in FIG. 4, which shows one image forming means Pa in detail, a laser beam is scanned in the direction of arrow B at a scanning speed ■ by a polygon mirror rotating at a constant speed in a laser scanner exposure means la. There are BD (beam detector) IQ2a and B on the upstream side in the scanning direction of the laser beam.
A D mirror 101a is disposed, and when a laser beam is incident on the BD 102a, it is placed from the BD 102a.

Next, the scanning start timing of the laser beam will be explained with reference to FIG. In FIG. 5, ■ represents a basic clock, which is obtained by a crystal oscillator 63 or the like that generates pulses at equal intervals. (2) In FIG. 4, the laser beam is reflected by the BD mirror 101a and the BD1
02a represents the BD scratch signal that occurs when the signal is captured. (2) shows how the image signal (video signal) starts scanning after the χ1 pulse of the basic clock (2) after being detected on the BD signal. Note that point P2 indicated by ■ is the fourth
This coincides with the image scanning start point P2 in the figure. (3) is based on the value of the signal level detected by the above-mentioned position detection means 2 of the transfer paper 41, and calculates the horizontal deviation position of the transfer paper 41 in the calculation unit 61 shown in FIG. The image signal starts scanning after χ2 pulses from the BD scratch signal P,) by advancing the lawn scanning start timing by ΔX2 pulses in the basic clock.

Here, as the position detection means 2 of the transfer paper 41, the above-mentioned end face detection is practical, and since it is practically difficult to detect the absolute value of the transfer paper 41 with respect to the device, it is preferable to use a relative value. do. Therefore, normally, a reference scanning start timing is set in advance, as shown in (■) in FIG. 5, and this timing is used as the reference timing.

As described in the conventional example, when the position of the paper feeder 40 shifts toward the front side of the main body in FIG. 2 (when a positional error occurs), the transfer paper 41 shifts toward the side a in FIG. 3. Assuming that this amount of deviation is △4, the position detection means 2 detects this amount of deviation Δρ.
is detected as a change in signal level. Based on the level change (deviation amount Δρ) of this signal, the arithmetic unit 61 of the timing control circuit shown in FIG.
A computation is electrically performed to advance the scan start timing by a pulse amount, and timing control shown in (2) in FIG. 5 is executed. Note that T6 is the pulse width of one pulse, and ■ is the scanning speed of the beam.

As a result, the amount of deviation Δ°C of the transfer paper 41 is corrected, and a toner image is actually formed on the transfer paper 41 at the same position as the reference mark (■) in FIG.

This is also to individually correct the positional deviation amount for each stage of the cassette case 42 of the paper feeder 40, and the value of the deviation amount Δ°C detected by the position detection means 2 is calculated by the calculation unit 61.
The initial value ΔC9χ2 calculated and electrically executed is registered in the RAM 64, the margin in the main scanning direction after the image is formed is measured by another measuring means, and the amount of deviation is calculated based on the measured value as described above. By controlling the arithmetic unit 61 to perform fine adjustment again, it is possible to individually correct the deviation in the main scanning direction for each stage of the cassette case 42 and form an image.

Therefore, according to this embodiment, the horizontal registration (
It is possible to adjust the alignment (horizontal alignment), can be used to increase the speed of the device, and has a simple configuration.It also prevents problems caused by the image protruding from the transfer paper due to misalignment of each paper feed tray (back dirt, etc.). It is possible to obtain effects such as preventing transport defects, etc.).

In the first embodiment of the present invention, an optical detection means is shown as the position detection means 2 of the transfer paper 41, but this position detection means rotates in contact with the end surface of the transfer paper 41. The transfer paper 4 can also be used in combination with a lever arm (not shown) and a potentiometer (not shown) that detects the rotation angle of the arm.
Needless to say, the position of point 1 can be detected.

(11) The present invention is widely applicable not only to electrophotographic color image forming apparatuses but also to digital monochrome printers (dot printers).

Further, as shown in FIG. 7, the recording material 41 is conveyed onto the recording material conveying device 30 while being gripped by a gripper 51, and a large number of ink ejection ports are arranged in a right angle direction substantially perpendicular to the moving direction of the recording material 41. Even in an image forming apparatus of the type that directly visualizes the image on the recording material 41 by scanning the image information in a direction perpendicular to the full line type inkjet using the RAD array 28, the scan start timing determines from which ink ejection port the image is printed. can be automatically adjusted based on the detected position of the recording material 41 in the same manner as in the first embodiment.

FIG. 7 shows the internal structure of a fifth embodiment of the present invention when the present invention is applied to an inkjet recording apparatus. In FIG. 7, 71 is an inkjet head with a width longer than the maximum recording paper width, 72 is a front-loading two-stage paper feed table, 73 is a conveyor belt, 74 is a registration roller, and 75 is a charging roller. be. In the above configuration, recording paper is fed from the paper feed table 72, the image timing is determined by the registration rollers 74, and the recording paper is conveyed from the registration rollers 74 and adsorbed to the conveyance belt 73 by the arm of the charging roller 7. An image is formed by the head 71.

Although this device does not have a means for detecting the position of the recording paper, since the inkjet head 71 is longer than the width of the recording paper,
The ink ejection location can be easily moved in the main scanning direction. Therefore, the initial value of the initial ejection point is registered in advance in RAM (not shown) for each paper feed table, and the margin after actual image formation is measured by a measuring means (not shown).
The configuration is such that the RAM value can be finely adjusted based on the measurement results.

Further, in this embodiment, the ink ejection timing in the sub-scanning direction for each paper feed table can be adjusted in relation to the operation timing of the registration roller 74 at the same time as the position adjustment in the main-scanning direction. Furthermore, the present invention can also be applied to an apparatus in which a plurality of registration rollers 74 are provided, and the same effects as those of the first embodiment can be obtained.

(Others) In particular, the present invention is an inkjet recording method that includes a means (for example, an electrothermal converter, a laser beam, etc.) for generating thermal energy as energy used for ejecting ink, This provides excellent effects in recording heads and recording apparatuses that use energy to cause changes in the state of ink. This is because such a system can achieve higher recording density and higher definition.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in a one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. This pulse-shaped drive signal is described in U.S. Pat. Nos. 4,463,359 and 4,345,262.
Those described in the specification are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the wafer is placed in a bending region. In addition, Japanese Patent Application Laid-Open No. 1989-5 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Application Laid-Open No. 59/1989 which discloses a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
The effects of the present invention are also effective even if the structure is based on the publication No.-138461. That is, regardless of the form of the recording head, according to the present invention, recording can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus.

Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally.

In addition, even with the serial type shown above, the recording head is fixed to the device body, or by being attached to the device body, electrical connection to the device body and ink supply from the device body are possible. The present invention is also effective when using a replaceable chip-type recording head, or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus, to the present invention, because the effects of the present invention can be further stabilized. Specifically, these include capping means for the recording head, cleaning means, pressure or suction means, preheating means using an electrothermal transducer or another heating element, or a combination thereof; It is also effective to perform a preliminary ejection mode in which ejection is performed separately from printing in order to perform stable printing.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done. That is, for example, the recording mode of the recording apparatus is not limited to a recording mode for only a mainstream color such as black, but may also be a recording mode in which the recording head is configured integrally or in a combination of multiple colors, The present invention is also extremely effective for devices equipped with at least one full color by color mixture.

Additionally, in the embodiments of the present invention described above,
Although ink is described as a liquid, it is an ink that solidifies at room temperature or below, but softens or liquefies at room temperature, or in an inkjet method, the ink itself is
Generally, the temperature is adjusted within the range of 0°C or more and 70°C or less so that the viscosity of the ink is within the stable ejection range, so even if the ink is in a liquid state when the recording signal is applied. Bye. In addition, the temperature increase caused by thermal energy can be actively prevented by using it as ρ energy to change the state of the ink from a solid state to a liquid state, or ink that solidifies when left standing is used to prevent ink evaporation. In any case, the ink is liquefied by applying thermal energy in accordance with the recording signal, and the liquid ink is ejected, or the ink has already begun to solidify by the time it reaches the recording medium. The present invention is also applicable when using ink that is liquefied only by energy. The ink used in this case is
Publication No. 4-56847 or JP-A-60-71260
As described in the above publication, the porous sheet may be held in a liquid or solid state in the recesses or through holes of the porous sheet and face the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to perform the above-mentioned film boiling method.

In addition, the inkjet recording apparatus of the present invention may take the form of an image output terminal for information processing equipment such as a computer, a copying apparatus combined with a reader, etc., or a facsimile apparatus having a transmitting/receiving function. It may also be something.

[Advantageous Effects of the Invention 1] As explained above, according to the present invention, the image forming timing can be adjusted for each paper feed tray, so alignment adjustment in the main scanning direction (horizontal direction) can be easily performed, and as a result, the manufacturing process can be improved. The cost can be reduced, the configuration can be simplified, and performance improvements such as increased speed can be achieved.

In particular, since inkjet recording utilizes ink bleeding, a slight deviation has a large effect on image quality. Particularly in the case of the piezo system, image quality deteriorates when variations in paper feed registration are added to variations in ejection characteristics.

On the other hand, inkjet systems that use thermal energy to form bubbles have good landing accuracy, but because they are dependent on temperature, many of them have driving condition changing means for fine adjustment. In this case, even if an attempt is made to correct variations in paper feed registration using these driving conditions, the variations in continuous paper feeding cannot be coped with, resulting in a decline in image quality. Therefore,
By applying the present invention, the range of correction of driving conditions can be made small, and there is an advantage that high-speed response can be appropriately performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of an embodiment of the present invention, FIG. 2 is a sectional view showing the internal structure of an image forming apparatus according to an embodiment of the present invention, and FIG. 3 is a diagram showing the recording material position in FIG. 2. FIG. 4 is a perspective view showing the detailed structure of the image forming means (scanner) shown in FIG. 2; FIG. 5 is a perspective view showing the detailed structure of the detection means; FIG. 6 is a block diagram showing the circuit configuration of the timing control circuit of the embodiment of the present invention shown in FIG. 1; FIG. FIG. 8 is a sectional view showing the internal structure of an image forming apparatus according to still another embodiment of the present invention. la to 1d... Laser scanner exposure means, 2... Position detection means, 3... Roller, 4... Conveyance belt, 5... Bias roller, 9a to 9d... Developing section, 16. ... Roller pair, 18a to 18d... Photosensitive drum, 30... Conveying device, 31... Adsorption charger, 40... Paper feeding device, 41... Recording paper (recording material), 42 ...Cassette case, 51...Gripper, 61...Arithmetic unit, 64...RAM. 65... Measuring means, 71... Inkjet head, 72... Paper feed table, 73... Conveyance belt, 74... Registration roller, 75... Charging roller, 102a-102d... Beam Detector (BD). A B
C Figure 1

Claims (1)

[Scope of Claims] 1) A recording material supplying means for supplying a recording material along with an image forming operation, a conveyance means for conveying the recording material supplied by the recording material supplying means to an image forming position, and the image forming In an image forming apparatus, the image forming apparatus includes an image forming means that is disposed at a position and forms an image by scanning in a main scanning direction perpendicular to a conveying direction of the recording material. It is characterized by comprising: a position detection means for detecting a position in the scanning direction; and a timing control means for changing the timing at which the image forming means starts scanning the image information based on the output information of the position detection means. image forming device. 2) It has a measuring means for measuring the amount of change in the image recording position in the main scanning direction on the recording material on which the image has been formed by the image forming means, and the timing controlling means, based on the measurement result of the measuring means, 2. The image forming apparatus according to claim 1, wherein the image information scanning start timing, which is a setting standard for each paper feeding section of the recording material supplying means, is changed and adjusted. 3) The recording head of the image forming means has means for generating thermal energy that causes film boiling in the ink as energy used for ejecting the ink. Image forming device.